Changing a bottom bracket to a cartridge unit.
 

I'm thinking of changing the bottom bracket on my 85 Sequoia to a cartridge unit but I'm not sure what I need.
The shell is 68 mm and the spindle is 114.5mm but as near as I can tell the drive side is 2mm longer than
the non drive side. Here is a photo of the spindle.
https://cimg5.ibsrv.net/gimg/bikefor...e4eed6822c.jpg

I think what you want is to preserve the length of the longer side, which means you'd want a 118mm (closest size).

And pay extra for a UN55 cartridge, instead of the UN26. You probably won't have to change it again.

[edit[ Also, that's assuming you have a JIS spindle and cranks, and not ISO. Not sure what's available in ISO.

May I ask whats the difference between a JIS spindle and an ISO spindle?

.
...personally, I usually do the slightly longer spindle thing, but it's also possible to shift the cartidge over a couple of mm by using a spacer or spacers on the drive side, that fits between the lip of the cartridge on that side and the BB shell. So then you can get away with a spindle closer to your original length. Look here for you question on JIS/ISO.

Not much difference, but enough to mess you up if you try and mix the two. The link that [MENTION=209177]3alarmer[/MENTION] gave should clarify.

Your spindle should be marked JIS, probably. What are the other markings?

Yes it is JIS . No other markings other than specialized 114.5 and 68

Actually, never mind about the ISO stuff...it's late and I'm tired. A Specialized Sequoia would almost certainly have a JIS spindle.

Vintage spindles were asymmetrical. Modern cartridge BB typically use a thicker drive side cup to shift the whole assembly to the drive side. This accomplishes the same thing, more or less. IOW a similar spindle length is probably going to work, or at least partly work. Unfortunately crank design has changed slightly too. Try and fit is the only safe method. If the crank has decent clearance now, I'd probably risk it with a 115 and a couple BB spacers, just in case. Might need 118 though. Hard to predict. This is something I usually recommend people take to their LBS, unless you're comfortable buying at least a couple BBs.

I can't remember who made the Specialized bottom brackets. Think it was Sugino. They won't necessarily be to a modern JIS standard.

Once you get a couple of them wrong and reorder you will start to have a little inventory to pick from on your next project. I was upset that I had guessed wrong and had to reorder the first time I replaced one, the second time I wasn't sure so I ordered 2 different ones. The next two times I had one in my stash that fit perfectly. Now I am back to square 1 on the next project:(

I also have found it preferable to choose the shorter spindle on the newer symmetric cartridges, and use a spacer on the drive side - it helps prevent the NDS crank arm sitting way too far outboard

Try phil wood
 

Take a look at thePhil Wood web site. I bet most of your questions will be answered. I put a Phil titanium bb on my Osell (campy crank)about 20 years ago and never looked back.
Cheers

I thought it might be easier to put in a new cartridge bottom bracket but after reading all
this I think Ill just replace the old bearings with new ones lol.I have it all taken apart
and everything seems to be in good shape.

...I never replace a cup and cone original with a sealed unit unless there's something wrong with the cups or the spindle. I know there are people who do, but I can't understand why.

I thought it might be easier but it doesn't seem that way to mebut I guess the sealed unit stays cleaner.

I'll assume you're using your existing crank and only replacing the BB

You have
114.5/2 = 57.25 = CL if it were symmetrical
Per your measurements 2mm longer on DS.

57.25 + 2 = 59.25 which would be CL for the longest end if symmetrical
59.25 X 2 = 118.5 for a symmetrical spindle
Do you have 0.5mm clearance on your DS?

You could also use a decent quality steel ruler, measure between the raised bearing bosses on the old spindle and mark a CL on the old spindle, then measure to the longest side and double it.